Premining and instamining (where they just start the coin with x coins in the devs wallet) are fairly common practices among new cryptocoins. They are usually frowned upon by the community but not always as the coin developers will sometimes keep a 1-2% for use promoting and developing the coin. Which most people consider fair. An 80% premine like bytecoin is ridiculous.
It is very easy to tell if a coin has been premined by checking the state of the block chain for the number of outstanding coins. The coins with large premines are usually outed withing an hour of their release.
I realize that, which is why I didn't believe the Bytecoin claims to have been used for years. (That and I spend a lot of time on Tor so I was skeptical I'd've never heard of it if there really was an active community using it.) But that didn't explain where the huge apparently-PoW-intensive blockchain came from.
It is very easy to tell if a coin has been premined by checking the state of the block chain for the number of outstanding coins. The coins with large premines are usually outed withing an hour of their release.